The sky looks a bit pixelated on my side and some jagged lines on the straight edges (loco / coach & bridge / bridge supports), with three distinctive fudgy areas under the bridge where the bridge supports begin. I have almost no experience with the scanning of slides (unlike yourself), so just my observations on looking at the rejected photo.

The whether the source of the image is a digital camera or film, the final image is the deciding factor. Based on your observations, I'll let this one go. Thanks.